"It could conceivably happen before [next weekend]," assistant general manager Scott Proefrock said Friday. "but again, I think that's not likely."
The 28-year-old Brown has hit .228 with five home runs in 63 games. Once a heralded prospect in the Phillies' system, his future with the team is uncertain, especially considering he will again be arbitration-eligible this offseason.
With just one month remaining, the odds of him taking the field again this season appear slim.
"It's going to be difficult for him to get back into action," Phillies interim manager Pete Mackanin said. "We'll just have to wait and see how mild or severe it is, or whatever his status is. The fact is that we've got other guys to see as well."
The players Mackanin references include outfielders Aaron Altherr and Darnell Sweeney, both of whom started Friday's series opener against the Red Sox. Brown's absence should create more opportunities for Altherr and Sweeney now that Cody Asche is expected to see more time at third base, and the team would like to see the pair play more alongside center fielder Odubel Herrera.
Jeff Francoeur will also work his way into the mix, but Mackanin felt more than comfortable with the veteran's body of work in 2015. Francoeur has hit .271 with 12 home runs and a .465 slugging percentage.
"He's done a fabulous job in his role," Mackanin said. "He doesn't need to prove anything to us or baseball. He's still a very good outfielder, and can contribute very well offensively. Those are check-marks that we don't have to worry about."
• Third baseman Maikel Franco (left wrist fracture) will be reevaluated by a doctor Tuesday after experiencing pain while swinging a bat earlier this week. Like Brown, Franco's chances of playing before the season ends appear doubtful.
"The closer we get to the end of the season, or the middle of September, the less likely it seems that he's even going to participate," Mackanin said. "But we're hopeful. If he's 100 percent with 10 days to go, I'd like to see him play."
Alec Shirkey is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.